In PatternSkin, it is easiest to add pattern_yuimenu to the SKIN setting
eg Set SKIN=pattern_yuimenu,pattern in your SitePreferences. To try it out,
add ?skin=pattern_yuimenu,pattern to the end of your URL -

Topic menu

This way, SideBarMenu can INCLUDE the $web.WebMenu if it exists, or (using warn=)
fall back to this topic, which will use the customised DefaultWebMenu topic in the Main or
fall back to the default in this topic